Method of winding transformers



Aug. 16,1927.

G. F. NIEMANN METHOD OF WINDING TRANSFORMERS Filed Sept. 25. 1926 Patented Aug. 16,1927.

UNITED STATES PATENT OFFICE.

GEORGE E. NIEMANN, OF CHICAGO, ILLINOIS, ASSIGNOR TO BENJAMIN ELECTRIC MFG; 00., OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

METHOD OF WINDING TRANSFORMERS.

Application ued September 25, 1926. Serial No. 137,672.

My invention relates to transformers, and particularly to transformers in which the primary and secondary coils are continuously wound on a mandrel or forming tool with a loop or slack portion taken from between the primary and secondary coils which, when severed, provides the required terminals be tween the same. 7

The object of myinvention is to provide a cheap, simple and efiicient transformer which can be rapidly wound on a rotating mandrel or forming tool sothat when the same is finished it presents the appearance of a substantially hollow tubular unit with the primary and secondary coils lying in substantially the same cylindrical plane.

A further object of my invention is to provide a transformer by rapidly rotating a mandrel or forming tool, and one wherein provision may be made for the terminals between the primary and secondary coils without the necessity of stopping the forming tool when the primary coil has been completed.

Other objects and advantages will be parent to those skilled in the art as my invention becomes better understood by the disclosures contained in the following specification when considered in connection with the accompanying drawing, in which Figure 1 is a broken side view of the forming tool with the transformer wound thereon and showing a portion of the same in cross section; and

Fig. 2 is a cross-sectional view of the same taken on the line 22 of Fig. 1. I

In considering the particular nature of the winding shown in the drawing, reference must be had to an application filed June 17, 1925, by Chester E. Warner and Arthur N. Nilson, Serial No. 37,640. Although I do not limit myself to this or any other particular form of coil, it will be readily appreciated that. transformers having uniform turns of wire, called in the trade single layer coiis, can be built by means of my invention in precisely the same manner.

My improved transformer is wound upon a forming tool 6 which has a series of slots 7 extending longitudinally of the same and partway through the body thereof so as to form fingers 8, and leaving at the rear thereof the cylindrical portion 9. The parmandrel 1st, having a tapered end 16 and a shoulder portion 15 at the outer end thereof,

' is adapted to be pressed between the fingers 8 in order to spread the same to the same diameter as the p0rti0n'9 shown in Fig. 1 for winding the transformer thereon,

The inner end of the forming tool 6 is placed in a chuck, or otherwise secured to the stock of an ordinary lathe, and continuously operated from the time the end 15 of the wire is attached to the pins 16 until the secondary coil has been completely wound and the finished transformer produced.

As stated, one end 15 of a supply of properly insulated wire is secured as by wrapping same around the pins 16 mounted on one of the'fingers 8 of the forming tool, or in any other desired manner, and the tool 6 is then rotated and the primary winding 17 produced, as shown in Fig. 1. This operation continues until the required number of turns has been placed there-on. Then the wire is drawn from the slot 11 in one of the fingers, the tool 6 continuing to rotate, and said wire is thrown back over and beyond the primary coil and one or two turns 18 wound thereon. This provides the slack wire for the terminals between the primary and secondary. Then the wire is again returned to the slot on the second succeeding finger and in line with the slot from which the slack portion at the end of the primary was formerly taken. The winding is then continued in the regular and described manner to form the secondary coil 19. After the secondary coil has been completed the primary and secondary coils are cemented together by brushing each of the portions of the coils, which lie above the slots 13, with cement 21, and the cement is then dried in any suitable manner and after the same is thoroughly dried the mandrel 1a is withdrawn. Upon Withdrawal of the mandrel 14; the fingers 8 spring inwardly so as to converge towards the center of the forming tool 6, and the completed transformer is disengaged from said fingers and falls from the said forming tool. now be severed so as to form the required terminals between the primary and secondary coils and the entire transformer will present the appearancepof a uniform tubular coil having a primary and secondary in cluded therein and built as a unitary construction. As a matter of fact, with the ex:- ception of a portion of one turn extending the Width of a single finger, there will be no break in the symmetrical winding of the turns of the primary and secondary.

It will be readily seen that by winding transformer by my improved method, above described, the entire transformer can be wound while continuously turning the mandrel and forming tool and no stop will be necessary for taking out the slack portion 18 which provides terminals between the primary and secondary coils.

I claim:

1. The herein described method of forming transformers comprising the steps of. :irst winding a primary coil consisting of the required number of turns upon a formtool, then winding a portion of wire at a: point remote from the primary coil; and then winding the secondary coil with its inner end contiguous to the outer end of the primary coil. Y i

2. The herein described process of windng a primary coil onto a rotating forming tool, then winding a portion of the wire to a point remote from the primary coil, and then returning to a point adjacent the primary coil and winding the secondary coil The extra turn 18 may on said forming tool, all in a continuous operation.

3. The herein described process of forming transformers consisting of winding the required number of turns to form the primary coil, then drawing the wire from the last turn of the primary coil to a point remote therefrom and binding a portion of said wire thereon, then returning said wire to a point adjacent said primary coil and in the same cylindrical plane thereof, and then winding the secondary coil thereon, all in a continuous operation.

4-. The hereindescribed process of forming transformers consisting of the steps of first winding a primary coil of the required number of turns onto a forming tool, then windmg a portion at a point remote from said primary coil, then winding a secondary coil in the same cylindrical plane and adjacent to the primary coil, and then cementing the turns of both coils together so as to form a unitary construction.

5. The herein described process of forming transformers consisting of the steps of first securing the end of the supply wire to a point on a revolvable forming tool and then revolving said forming tool to form the primary winding thereon, then drawing said Wire over said wound primary coil and. winding portion at a point remote from said primary coil, then drawing said wire across said primary coil to a point in line with the point at which the wire was drawn froin the end of said primary coil, and then winding the required number of turns to form the secondary coil, all in a continuous operation.

In witness whereof, I have hereunto subscribed. my name.

GEORGE F. NIEMANN. 

